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  • Hyperthyroidism
    • Causes
      • Excess release of thyroid hormone as seen in Graves’ disease, multinodular goiter, toxic adenoma, thyroiditis, pituitary thyrotropin (rare), iodine induced (amiodarone or angiographic contrast media), pregnancy induced
    • Signs and symptoms
      • Goiter
      • Sweating
      • Tachycardia, nervousness
      • Bowel or menstrual problems
      • Eye symptoms (ophthalmopathy)
      • Dermopathy
      • Skeletal muscle weakness
      • Vasodilation
      • Heat intolerance
    • Preoperative
      • Treat with anti-thyroid drugs, surgery, or radiation to reduce thyroid tissue
        • Propylthiouracil (PTU), methimazole, and carbimazole can be used to inhibit organification of iodide and synthesis of hormone
      • At least 6–8 weeks are required to regulate thyroid levels in most hyperthyroid patients
      • Optimal duration of anti-thyroid drug therapy for Graves’ disease is 12–18 months with low dose therapy to prevent relapse
      • Beta-blockers should be used in all hyperthyroid patients to attenuate excessive sympathetic activity unless contraindicated. Goal is HR < 90 bpm
        • Propranolol also impairs the peripheral conversion of T4 to T3 over 1–2 weeks
      • Potassium iodide can be used prior to surgery to reduce circulating thyroid hormone and cardiovascular symptoms
      • Glucocorticoids (dexamethasone 8–12 mg/day) can be used in severe thyrotoxicosis to reduce hormone secretion and peripheral conversion of T4 to T3
      • Thorough airway exam is necessary in anticipation of a difficult airway in those patients with goiters, especially substernal goiters. It may be necessary to perform an awake fiberoptic intubation or an inhalation induction
    • Intraoperative
      • All anti-thyroid medications should be continued through morning of surgery
      • General anesthesia with tracheal intubation and muscle relaxation is the most popular anaesthetic technique for thyroidectomy. A small reinforced tracheal tube may be needed if there is some degree of tracheal compression present
      • The incidence of temporary unilateral vocal cord paralysis resulting from damage to the recurrent laryngeal nerve (RLN) is 3–4%. Intraoperative electro-physiological monitoring of the RLN can be done with the use of a tracheal tube with integrated EMG electrodes positioned at the level of the vocal cords. When the RLN has been identified, the nerve is stimulated until an EMG response is obtained
      • Anesthetic goal is to keep patient deep enough to avoid exaggerated sympathetic response to surgical stimuli
        • Hyperthyroidism does NOT increase MAC requirements
      • Avoid medications that may stimulate the nervous system, such as pancuronium and ketamine
        • Avoid histamine releasing drugs as well, such as atracurium and vancomycin
      • Treat hypotension with direct-acting vasopressors, rather than those that indirectly release catecholamines
      • May need to use reduced dose of muscle relaxant initially, and use a nerve stimulator to guide subsequent muscle relaxant doses
      • Some surgeons perform thyroid surgery under MAC and cervical plexus block. Typically, a superficial cervical plexus block will be performed on the side with the smaller goiter or nodule, and both a deep and superficial cervical plexus block on the larger side. Avoid bilateral deep blocks, as this would block the phrenic nerve bilaterally
    • Postoperative
      • Complications of thyroidectomy include recurrent laryngeal nerve damage, tracheal compression due to hematoma or tracheomalacia, and hypoparathyroidism
      • Iatrogenic hypoparathyroidism may result in hypocalcemia manifesting as laryngeal stridor progressing to laryngospasm within the first 24–96 hours post op
      • To assess recurrent laryngeal nerve damage, ...

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